|18 Aug 1846 - During the war with [[Mexico]], the US took control of Santa Fe and proclaimed sovereignty over the land that later became the [[New Mexico]] Territory.<ref>Williams 108-110</ref> Look for records in the [http://www.archives.gov/ National Archives and Records Administration], the Mexico [[Mexico Archives and Libraries|Archives]] and the [http://www.nmcpr.state.nm.us/archives/archives_hm.htm New Mexico State Records Center and Archives].

|18 Aug 1846 - During the war with [[Mexico]], the US took control of Santa Fe and proclaimed sovereignty over the land that later became the [[New Mexico]] Territory.<ref>Williams 108-110</ref> Look for records in the [http://www.archives.gov/ National Archives and Records Administration], the Mexico [[Mexico Archives and Libraries|Archives]] and the [http://www.nmcpr.state.nm.us/archives/archives_hm.htm New Mexico State Records Center and Archives].

Previous Jurisdictions and Record Repositories

Identify the jurisdiction covering the land when and where your ancestor lived

Determine the record repositories for that jurisdiction in the present day

For example, suppose you were told your ancestor lived in Tucson, Arizona Territory in 1861.

In the present day, Tucson is indeed located in Arizona. But Arizona didn't exist in 1861. Arizona Territory wasn't created until 1863. Before that, the land belonged to New Mexico Territory, which was created in 1850. So your ancestor lived in New Mexico Territory. This jurisdiction still exists today as the State of New Mexico.

In 1853, the US bought the Gadsden Purchase from Mexico, which contained land south of the Gila River. This is the land where Tucson is located. In 1854, this land was given to New Mexico Territory and in 1855 this land was added to Dona Ana county. Then in 1860, New Mexico created Arizona county from the land in Dona Ana county. Arizona County existed totally within the present day State of Arizona. So your ancestor lived in Arizona County in the New Mexico Territory.

But Arizona county was discontinued in 1862, then recreated in 1863 and finally discontinued again when Arizona Territory was created in 1863. The records from this extinct county reverted to Dona Ana County, which still exists in the State of New Mexico.

Putting this all together, your ancestor actually lived in Tucson, Arizona County, New Mexico Territory in 1861. Therefore look for records at the archives in Tucson, Dona Ana County, and the State of New Mexico.

Sometimes, records were recorded in a county or jurisdiction where your ancestor did not live. Maybe there was confusion as to where the borders lay. Or maybe it was a shorter distance to the neighboring county seat. There could be several reasons, so don't overlook records in nearby jurisdictions. But treat this as the exception to the rule and check the most obvious place first.

From the 1600s to 1846 - Spanish and Mexican land that would later become Arizona

From the 1600's, Spain laid claim to much of the land in present day southwestern US. But because of the great distances and the hostilities of the Indian tribes, Spanish rule effectively extended only to the southern portion of present day Arizona, and sometimes not even that much. Tucson was the only permanent town established, because of the military garrison there.

Spain established the practice of giving land grants to encourage settlement on the fringes of their rule. Mexico continued this practice. All Spanish and Mexican land grants for present day Arizona were located in the Gadsden Purchase. Stand in downtown Tucson and and look toward the southeast corner of present day Arizona, then turn 90 degrees to the west. All of these Spanish and Mexican Land Grants are located in that triangle.

1820 - The San Ignacio de la Canoa Grant. Two brothers petitioned the governor of Sonora/Sinaloa for four leagues (sitios) to raise cattle and horses. Title was issued by Mexico in 1849 and Court of Private Land Claims confirmed the grant for 17,204 acres in 1899. This land grand was located on both sides of Interstate 19 south of Green Valley (that town is in the northwest corner of the grant).

1820 - The San Bernardino Grant south of Bisbee was also applied for by Ignacio de Perez, a Spanish lieutenant, who paid $90 for four leagues. The grant was surveyed in 1821 and recorded in Arizpe, Sonora but no title was ever issued. Most of the grant is located south of the border. The Court of Private Land Claims confirmed 2,383 acres that are on the American side.

1821 - Southwest of Patagonia is the San José de Sonoita Grant, the smallest grant made in Arizona. It was applied for in 1821 by Leon Herreras, a resident of Tubac, who had it surveyed and who received a Mexican title in 1825 for 7,598 acres. Court of Private Land Claims rejected that title on the grounds that the treasurer of Sonora had no authority to sell land in that area, but U. S. Supreme Court overturned the rejection. However it only confirmed 5,123 acres.

1821 - The San Rafael de la Zanja Grant, just to the north of the Mexican border, east of the Patagonia Mountains. The four-league grant was sold at public auction for $1,297 and title was issued by Mexico in 1825. Court of Private Land Claims confirmed 17,352 acres of the grant in 1902.

24 Aug 1821 - The Treaty of Cordoba was signed by Spain, which recognized Mexico's independence.[1] The land in present day Arizona became part of Mexico, north of the Gila River was in the State of Alta California and south of the Gila River was in the State of New Navarra. Look for records in the Spain and Mexico Archives.

1827 - The San Ignacio del Babocomari Grant looks on a map like a twenty miles long boomerang north and west of present day Fort Huachuca. In 1827, Ignacio Elías y Gonzales and his sister Lulalia paid $380 for this nearly fifty-three square miles grant. The title to the grant was issued by the treasurer general of Sonora, Mexico on 25 December 1832. The Court of Private Land Claims confirmed 33,792 acres for this grant.

1827 - The San Juan de las Boquillas y Nogales Grant is located along the San Pedro River west of Tombstone. Title was issued to Ignacio Elías y Gonzales in 1833. The Court of Private Land Claims confirmed 17,354 acres for this grant.

1827 - The San Rafael del Valle Grant is adjoined to the San Juan grant on the south. Title was issued in 1832. The San Rafael Grant was at first rejected by Court of Private Land Claims, but the rejection was overturned in the U.S. Supreme Court, who confirmed 17,475 acres for this grant.

24 October 1831 - The Buena Vista Grant straddles the international boundary just east of Nogales and two thirds of it is in Mexico. This Mexican land grant was made to Dona Josefa Morales. It consisted of 18,640 acres and was also known as the Maria Santissima del Carmen Land Grant. Following the Gadsden Purchase, the Court of Private Land Claims confirmed 5,733 acres of the grant to men named Maish and Driscoll.

From 1846 to 1863 - New Mexico Territory land that would later become Arizona

13 Dec 1850 - The US created the New Mexico Territory from unorganized federal land.[4] This territory named after the Mexican State of New Mexico. Some counties were created, but they were small and covered land only in present day New Mexico. The land in the present day Arizona was at that time non-county land. Also the land south of the Gila River still belonged to Mexico. Look for records in the Mexico Archives and the New Mexico State Records Center and Archives.

3 Feb 1855 - Dona Ana County gained all the land acquired in the Gadsden Purchase.[9] Its boundary was stretched across present day Arizona to the Baja California border. Look for records in Dona Ana County.

22 Dec 1865 - Arizona created Pah-Ute County from the northern half of Mohave County.[17] This county named for the Paiute Indians, using the spelling of that day. Both Mohave and Pah-Ute counties covered land which was later given to Nevada. Look for records in Mohave County.

14 Feb 1871 - Arizona created Maricopa County from land in Yavapai County.[20] This county named for the Maricopa Indians. Look for records in Maricopa and Yavapai counties. 18 Feb 1871 - Arizona discontinued Pah-Ute County.[21] In effect, withdrawing claim to that land after exhausting all legal recourse. The remnant of Pah-Ute County still in Arizona was returned to Mohave County. Look for records in Mohave County.